Methods and systems for beamformed system information transmission

ABSTRACT

A method and apparatus for use in a wireless transmit receive unit (WTRU) for receiving system information. A WTRU receives a broadcast signal from a gNB, wherein the broadcast signal includes system information. The WTRU determines configuration information associated with the received system information and the WTRU transmits a signal to the gNB using the determined configuration information associated with the received system information. The configuration information includes an indication regarding whether the WTRU is able to include any one or a combination of a request signal or a feedback signal in the signal transmitted to the gNB. The transmitted signal to the gNB may include a preamble that indicates system information block (SIB) request information. The transmitted signal to the gNB may include a control field that indicates additional SIB request information. The transmitted signal may provide feedback for the received system information. The WTRU then receives system information from the gNB in response to the transmitted signal. The received system information in response to the transmitted signal is one or more SIBs.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application No.62/401,094 filed Sep. 28, 2016 and U.S. provisional application No.62/416,557 filed Nov. 2, 2016, the contents of which are herebyincorporated by reference herein.

BACKGROUND

A broad classification of use cases for emerging 5G New Radio (NR)systems include, but are not limited to, the following: Enhanced MobileBroadband (eMBB), Massive Machine Type Communications (mMTC) and UltraReliable and Low latency Communications (URLLC). The use cases are basedon general requirements set out by ITU-R, NGMN, and 3GPP. The differentuse cases may focus on different requirements such as higher data rate,higher spectrum efficiency, low power and higher energy efficiency,lower latency and higher reliability. A wide range of spectrum bandsranging from 700 MHz to 80 GHz are being considered for a variety ofdeployment scenarios.

It is well known that as the carrier frequency increases, severe pathloss becomes a crucial limitation to guarantee the sufficient coveragearea. Transmissions in millimeter wave systems could additionally sufferfrom non-line-of-sight losses, (e.g., diffraction loss, penetrationloss, Oxygen absorption loss, foliage loss, and the like). Duringinitial access, a base station and a wireless transmit/receive unit(WTRU) need to overcome these high path losses and discover each other.Utilizing dozens or even hundreds of antenna elements to generate a beamformed signal is an effective way to compensate the severe path loss byproviding significant beam forming gain. Beamforming techniques mayinclude digital, analog and hybrid beamforming. After initial access,the WTRU proceeds to receive system information from the base stationover a logical channel broadcast control channel (BCCH).

SUMMARY

A method and apparatus for use in a wireless transmit receive unit(WTRU) for receiving system information. A WTRU receives a broadcastsignal from a gNB, wherein the broadcast signal includes systeminformation. The WTRU determines configuration information associatedwith the received system information and the WTRU transmits a signal tothe gNB using the determined configuration information associated withthe received system information. The configuration information includesan indication regarding whether the WTRU is able to include any one or acombination of a request signal or a feedback signal in the signaltransmitted to the gNB. The transmitted signal to the gNB may include apreamble that indicates system information block (SIB) requestinformation. The transmitted signal to the gNB may include a controlfield that indicates additional SIB request information. The transmittedsignal may provide feedback for the received system information. TheWTRU then receives system information from the gNB in response to thetransmitted signal. The received system information in response to thetransmitted signal is one or more SIBs. The received system informationin response to the transmitted signal is received periodically indefined locations or aperiodically.

The preamble may be associated with one or more SIBs. The preamble mayindicate SIB request information. The preamble may be associated withone or more groups of SIBs, each group of SIBs being associated with apriority level. The configuration information may include mappinginformation that provides an association between the preamble and one ormore SIBs.

The WTRU may receive the broadcast signal in one or more directionalbeams and the feedback signal included in the transmitted signalprovides feedback for one or more directional beams. The feedbackincludes any one or a combination of beam information associated withthe WTRU and an indication regarding whether the received first systeminformation satisfies reception criteria. The reception criteriaincludes a detected energy of the first system information being above apredetermined threshold. The reception criteria includes a cyclicredundancy check (CRC) associated with the first system informationbeing passed.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawings,wherein like reference numerals in the figures indicate like elements,and wherein:

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram illustrating an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to an embodiment;

FIG. 1C is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to an embodiment;

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to an embodiment;

FIG. 2 shows a flow chart diagram of a selective beam sweeping basedsystem information transmission;

FIG. 3 shows a flow chart diagram of a selective beam sweeping basedsystem information transmission using an updated beam state;

FIG. 4 is a beam state transition table that shows the states of a beamwhen using selective beam sweeping;

FIG. 5 is a beam state transition table that shows the states of a beambased on a data detection state;

FIG. 6 is a beam state transition table that shows the states of a beambased on based on a data detection state and energy;

FIG. 7 shows a flow chart diagram of a selective beam sweeping basedsystem information transmission based on a data detection state andenergy of a WTRU;

FIG. 8 shows a timing diagram of ACK to SIB process used for SIBtransmissions;

FIG. 9 shows a timing diagram of an example non-autonomous HARQ processused for SIB transmissions;

FIG. 10 shows a timing diagram of another example non-autonomous HARQprocess used for requesting SIB transmissions;

FIG. 11 shows a timing diagram of an example of an ACK that is used torequest a next SIB transmission;

FIG. 12 shows a flow chart diagram of an example of method for use in agNB and one or more WTRUs for signaling system information in order toenable efficient beam sweeping;

FIG. 13 shows a flow chart diagram of an example of a method for use ina gNB to dynamically determine the Polar encoding scheme for SIBs;

FIG. 14 shows a diagram of an example of Polar mapping function thatmaps SIBs to the input bit channels of multiple Polar codes;

FIG. 15 shows a flow chart diagram of an example of system informationtransmission and processing in a gNB;

FIG. 16 shows a signaling diagram of an example message flow between agNB and multiple WTRUs for a SIB transmission;

FIG. 17 shows a flow chart diagram of using predefined time locationsfor SIB transmissions;

FIG. 18 shows a flow chart diagram of using periodic time locations forSIB transmissions; and

FIG. 19 shows a flow chart diagram of an example method for use in a gNBand one or more WTRUs for signaling system information.

DETAILED DESCRIPTION

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word discrete Fourier transform Spread OFDM (ZT-UW-DFT-S-OFDM),unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bankmulticarrier (FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network (CN) 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d, any of which maybe referred to as a station (STA), may be configured to transmit and/orreceive wireless signals and may include a user equipment (UE), a mobilestation, a fixed or mobile subscriber unit, a subscription-based unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watchor other wearable, a head-mounted display (HMD), a vehicle, a drone, amedical device and applications (e.g., remote surgery), an industrialdevice and applications (e.g., a robot and/or other wireless devicesoperating in an industrial and/or an automated processing chaincontexts), a consumer electronics device, a device operating oncommercial and/or industrial wireless networks, and the like. Any of theWTRUs 102 a, 102 b, 102 c and 102 d may be interchangeably referred toas a UE.

The communications system 100 may also include a base station 114 aand/or a base station 114 b. Each of the base stations 114 a, 114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to oneor more communication networks, such as the CN 106, the Internet 110,and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a NodeB, an eNode B(eNB), a Home Node B, a Home eNode B, a next generation NodeB, such as agNode B (gNB), a new radio (NR) NodeB, a site controller, an accesspoint (AP), a wireless router, and the like. While the base stations 114a, 114 b are each depicted as a single element, it will be appreciatedthat the base stations 114 a, 114 b may include any number ofinterconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, and the like. The base station 114 a and/or the base station 114b may be configured to transmit and/or receive wireless signals on oneor more carrier frequencies, which may be referred to as a cell (notshown). These frequencies may be in licensed spectrum, unlicensedspectrum, or a combination of licensed and unlicensed spectrum. A cellmay provide coverage for a wireless service to a specific geographicalarea that may be relatively fixed or that may change over time. The cellmay further be divided into cell sectors. For example, the cellassociated with the base station 114 a may be divided into threesectors. Thus, in one embodiment, the base station 114 a may includethree transceivers, i.e., one for each sector of the cell. In anembodiment, the base station 114 a may employ multiple-input multipleoutput (MIMO) technology and may utilize multiple transceivers for eachsector of the cell. For example, beamforming may be used to transmitand/or receive signals in desired spatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink(DL) Packet Access (HSDPA) and/or High-Speed Uplink (UL) Packet Access(HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/orLTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as NR Radio Access , which mayestablish the air interface 116 using NR.

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement multiple radio access technologies. For example, thebase station 114 a and the WTRUs 102 a, 102 b, 102 c may implement LTEradio access and NR radio access together, for instance using dualconnectivity (DC) principles. Thus, the air interface utilized by WTRUs102 a, 102 b, 102 c may be characterized by multiple types of radioaccess technologies and/or transmissions sent to/from multiple types ofbase stations (e.g., an eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106.

The RAN 104 may be in communication with the CN 106, which may be anytype of network configured to provide voice, data, applications, and/orvoice over internet protocol (VoIP) services to one or more of the WTRUs102 a, 102 b, 102 c, 102 d. The data may have varying quality of service(QoS) requirements, such as differing throughput requirements, latencyrequirements, error tolerance requirements, reliability requirements,data throughput requirements, mobility requirements, and the like. TheCN 106 may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the CN 106 may be in direct or indirectcommunication with other RANs that employ the same RAT as the RAN 104 ora different RAT. For example, in addition to being connected to the RAN104, which may be utilizing a NR radio technology, the CN 106 may alsobe in communication with another RAN (not shown) employing a GSM, UMTS,CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN 106 may also serve as a gateway for the WTRUs 102 a, 102 b, 102c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired and/or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another CN connected to one or more RANs, whichmay employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1A may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad 128, non-removable memory 130, removable memory 132,a power source 134, a global positioning system (GPS) chipset 136,and/or other peripherals 138, among others. It will be appreciated thatthe WTRU 102 may include any sub-combination of the foregoing elementswhile remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), anyother type of integrated circuit (10), a state machine, and the like.The processor 118 may perform signal coding, data processing, powercontrol, input/output processing, and/or any other functionality thatenables the WTRU 102 to operate in a wireless environment. The processor118 may be coupled to the transceiver 120, which may be coupled to thetransmit/receive element 122. While FIG. 1B depicts the processor 118and the transceiver 120 as separate components, it will be appreciatedthat the processor 118 and the transceiver 120 may be integratedtogether in an electronic package or chip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In an embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and/or receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 1B as asingle element, the WTRU 102 may include any number of transmit/receiveelements 122. More specifically, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as NR and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The peripherals 138 may include one ormore sensors. The sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor, an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, ahumidity sensor and the like.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) and DL(e.g., for reception) may be concurrent and/or simultaneous. The fullduplex radio may include an interference management unit to reduce andor substantially eliminate self-interference via either hardware (e.g.,a choke) or signal processing via a processor (e.g., a separateprocessor (not shown) or via processor 118). In an embodiment, the WTRU102 may include a half-duplex radio for which transmission and receptionof some or all of the signals (e.g., associated with particularsubframes for either the UL (e.g., for transmission) or the DL (e.g.,for reception)).

FIG. 1C is a system diagram illustrating the communication system 100including a RAN 113 and a CN 115 according to an embodiment. As notedabove, the RAN 113 may employ an E-UTRA radio technology to communicatewith the WTRUs 102 a, 102 b, 102 c over the air interface 116. The RAN113 may also be in communication with the CN 115.

The RAN 113 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 113 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 10, the eNode-Bs 160a, 160 b, 160 c may communicate with one another over an X2 interface.

The CN 115 shown in FIG. 10 may include a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (PGW) 166. While the foregoing elements are depicted as part ofthe CN 115, it will be appreciated that any of these elements may beowned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 162 a, 162 b, 162 cin the RAN 113 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 113 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 113 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 102 b, 102 c, managing and storing contexts of theWTRUs 102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 115 may facilitate communications with other networks. Forexample, the CN 115 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 115 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 115 and thePSTN 108. In addition, the CN 115 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have access or an interface to a Distribution System(DS) or another type of wired/wireless network that carries traffic into and/or out of the BSS. Traffic to STAs that originates from outsidethe BSS may arrive through the AP and may be delivered to the STAs.Traffic originating from STAs to destinations outside the BSS may besent to the AP to be delivered to respective destinations. Trafficbetween STAs within the BSS may be sent through the AP, for example,where the source STA may send traffic to the AP and the AP may deliverthe traffic to the destination STA. The traffic between STAs within aBSS may be considered and/or referred to as peer-to-peer traffic. Thepeer-to-peer traffic may be sent between (e.g., directly between) thesource and destination STAs with a direct link setup (DLS). In certainrepresentative embodiments, the DLS may use an 802.11e DLS or an 802.11ztunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may nothave an AP, and the STAs (e.g., all of the STAs) within or using theIBSS may communicate directly with each other. The IBSS mode ofcommunication may sometimes be referred to herein as an “ad-hoc” mode ofcommunication.

When using the 802.11ac infrastructure mode of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width. The primarychannel may be the operating channel of the BSS and may be used by theSTAs to establish a connection with the AP. In certain representativeembodiments, Carrier Sense Multiple Access with Collision Avoidance(CSMA/CA) may be implemented, for example in 802.11 systems. ForCSMA/CA, the STAs (e.g., every STA), including the AP, may sense theprimary channel. If the primary channel is sensed/detected and/ordetermined to be busy by a particular STA, the particular STA may backoff. One STA (e.g., only one station) may transmit at any given time ina given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. Thechannel operating bandwidths, and carriers, are reduced in 802.11af and802.11ah relative to those used in 802.11n, and 802.11ac. 802.11afsupports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications (MTC), such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode) transmitting to the AP, all available frequency bands may beconsidered busy even though a majority of the available frequency bandsremains idle.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 1D is a system diagram illustrating the communication system 100including a RAN 117 and a CN 119 according to an embodiment. As notedabove, the RAN 117 may employ an NR radio technology to communicate withthe WTRUs 102 a, 102 b, 102 c over the air interface 116. The RAN 117may also be in communication with the CN 119.

The RAN 117 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 117 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 108 b may utilize beamforming to transmit signals to and/orreceive signals from the gNBs 180 a, 180 b, 180 c. Thus, the gNB 180 a,for example, may use multiple antennas to transmit wireless signals to,and/or receive wireless signals from, the WTRU 102 a. In an embodiment,the gNBs 180 a, 180 b, 180 c may implement carrier aggregationtechnology. For example, the gNB 180 a may transmit multiple componentcarriers to the WTRU 102 a (not shown). A subset of these componentcarriers may be on unlicensed spectrum while the remaining componentcarriers may be on licensed spectrum. In an embodiment, the gNBs 180 a,180 b, 180 c may implement Coordinated Multi-Point (CoMP) technology.For example, WTRU 102 a may receive coordinated transmissions from gNB180 a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containing avarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c).In the standalone configuration, WTRUs 102 a, 102 b, 102 c may utilizeone or more of gNBs 180 a, 180 b, 180 c as a mobility anchor point. Inthe standalone configuration, WTRUs 102 a, 102 b, 102 c may communicatewith gNBs 180 a, 180 b, 180 c using signals in an unlicensed band. In anon-standalone configuration WTRUs 102 a, 102 b, 102 c may communicatewith/connect to gNBs 180 a, 180 b, 180 c while also communicatingwith/connecting to another RAN such as eNode-Bs 160 a, 160 b, 160 c. Forexample, WTRUs 102 a, 102 b, 102 c may implement DC principles tocommunicate with one or more gNBs 180 a, 180 b, 180 c and one or moreeNode-Bs 160 a, 160 b, 160 c substantially simultaneously. In thenon-standalone configuration, eNode-Bs 160 a, 160 b, 160 c may serve asa mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a, 180 b,180 c may provide additional coverage and/or throughput for servicingWTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, DC, interworking between NR andE-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184 b, routing of control plane information towards Access andMobility Management Function (AMF) 182 a, 182 b and the like. As shownin FIG. 1D, the gNBs 180 a, 180 b, 180 c may communicate with oneanother over an Xn interface.

The CN 119 shown in FIG. 1D may include at least one AMF 182 a, 182 b,at least one UPF 184 a, 184 b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whilethe foregoing elements are depicted as part of the CN 119, it will beappreciated that any of these elements may be owned and/or operated byan entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 117 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different protocol data unit (PDU)sessions with different requirements), selecting a particular SMF 183 a,183 b, management of the registration area, termination of non-accessstratum (NAS) signaling, mobility management, and the like. Networkslicing may be used by the AMF 182 a, 182 b in order to customize CNsupport for WTRUs 102 a, 102 b, 102 c based on the types of servicesbeing utilized WTRUs 102 a, 102 b, 102 c. For example, different networkslices may be established for different use cases such as servicesrelying on ultra-reliable low latency (URLLC) access, services relyingon enhanced massive mobile broadband (eMBB) access, services for MTCaccess, and the like. The AMF 182 a, 182 b may provide a control planefunction for switching between the RAN 117 and other RANs (not shown)that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro,and/or non-3GPP access technologies such as WiFi.

The SMF 183 a, 183 b may be connected to an AMF 182 a, 182 b in the CN119 via an N11 interface. The SMF 183 a, 183 b may also be connected toa UPF 184 a, 184 b in the CN 119 via an N4 interface. The SMF 183 a, 183b may select and control the UPF 184 a, 184 b and configure the routingof traffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b mayperform other functions, such as managing and allocating UE IP address,managing PDU sessions, controlling policy enforcement and QoS, providingDL data notifications, and the like. A PDU session type may be IP-based,non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 117 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering DL packets, providing mobility anchoring, and the like.

The CN 119 may facilitate communications with other networks. Forexample, the CN 119 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 119 and the PSTN 108. In addition, the CN 119may provide the WTRUs 102 a, 102 b, 102 c with access to the othernetworks 112, which may include other wired and/or wireless networksthat are owned and/or operated by other service providers. In oneembodiment, the WTRUs 102 a, 102 b, 102 c may be connected to a local DN185 a, 185 b through the UPF 184 a, 184 b via the N3 interface to theUPF 184 a, 184 b and an N6 interface between the UPF 184 a, 184 b andthe DN 185 a, 185 b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d, Base Station 114 a-b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-b, UPF 184a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation devices may performthe one or more, or all, functions while being fully or partiallyimplemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

In LTE systems, system information (SI) is broadcasted by an eNB over alogical channel BCCH. This logical channel information is furthercarried over a transport channel (e.g., a broadcast channel (BCH)) orcarried by a downlink shared control channel (DL-SCH). There are twoparts in SI: a static part and a dynamic part. The static part is calleda master information block (MIB) and is transmitted using BCH andcarried by a physical broadcast channel (PBCH) once every 40 ms. The MIBcarries useful information which includes channel bandwidth, physicalhybrid-ARQ indicator channel (PHICH) configuration details, transmitpower, number of antennas, and system information block (SIB) schedulinginformation transmitted along with other information on the DL-SCH. Thedynamic part is called a SIB and is mapped on radio resource control(RRC) SI messages over a DL-SCH (e.g., SI-1, SI-2, SI3, etc.) and istransmitted using a physical downlink shared channel (PDSCH) at periodicintervals. For example, SI-1 is transmitted every 80 ms, SI-2 istransmitted every 160 ms and SI-3 is transmitted every 320 ms.

In LTE systems, there are 13 types of system information blocks (SIBs),which helps WTRUs to access a cell, perform cell re-selection,information related to INTRA-frequency, INTER-frequency and INTER-RATcell selections. Each SIB has its own job to do, (i.e., each SIB ismeant to carry information which is related to perform their assignedjob). After initial cell synchronization and reading a MIB, a WTRUproceeds to read SIBs to obtain important cell access relatedparameters. For example, SIB1 broadcasts common information to all WTRUs in the cell related to cell access parameters and information relatedto scheduling of other SIBs. Hereinafter, the terms system informationtransmission and SIB transmission may be used interchangeably.

The following properties need to be considered for an initial accesssignal design in NR systems.

An initial access signal design in NR systems should minimize analways-on signal for system information. This improves the networkenergy efficiency as it transmits a system information signal only whenneeded. In addition, it supports forward compatibility since theresources can be flexibly scheduled for legacy or new signals.

The initial access related signals in NR systems should also betransmitted with a beam-based transmission scheme. Due to coverage lossfrom severe pathloss in high frequency, beamforming may need to be usedto compensate the pathloss even for initial access signals (e.g., PBCHand SIBs).

The initial access signal design in NR systems also needs to efficientlytransmit system information in order to reduce beam sweep overhead andsave power. A beam sweeping mechanism could be used to cover a cell inwhich all beams in a cell are swept to transmit a signal. However, thismay result in unnecessary energy consumption. The energy loss orresource waste from beam sweeping should be minimized.

The initial access signal design in NR systems should also enhance SIBperformance for critical information (e.g., use of one or more SIBs andeach SIB has a different priority level).

In NR systems, a broadcasting channel may be an always-on signal whichmay be transmitted periodically in a predefined time/frequencylocations. This always-on signal may unnecessarily waste time/frequencyresources and network energy in an NR system if there is no WTRUrequiring the broadcasting signal. Accordingly, a WTRU request-basedbroadcasting signal transmission may be used to minimize always-onsignals in a network.

In a beam-based system, a sweeping of all beams used in the system forbroadcasting signal transmission may need to be supported, where eachbeam may cover a specific location within a cell coverage area. In thiscase, sweeping of all beams when the broadcasting signals are requestedfor a subset beams may result in system throughput loss and networkenergy waste.

A beam sweeping mechanism or beam sweeping refers to the sending ortransmitting of a signal with a set of beams, where the set of beams maybe used, selected, determined, or transmitted in a different time and/orfrequency domain. In an example, beam sweeping describes that a signaltransmission is transmitted with a set of beams in consecutive timeresources. Hereafter, a full beam sweeping may be a beam sweeping with afull set of beams (e.g., all beams used for a signal transmission) and apartial beam sweeping may be a beam sweeping with a subset of beams(e.g., a subset of beams used for a signal transmission). A partial beamsweeping, selective beam sweeping, subset beam sweeping, and active beamsweeping may be used interchangeably.

NR systems may use a selective beam sweeping with a periodicbroadcasting signal. For example, a broadcasting signal may betransmitted periodically in a predefined or a configured time/frequencyresources and a set of beams may be used in each period for thebroadcasting signal, wherein the set of beams may be determineddynamically or semi-statically. The use of a periodic broadcastingsignal may reduce always-on signals in the system.

A beam that may be used for a broadcasting signal (e.g., a beam in theset of beams for beam sweeping) in a period may be referred to as anactive beam and/or an active status. A beam that may be unused for abroadcasting signal (e.g., a beam not in the set of beams for beamsweeping) in a period may be referred to as an inactive beam and/or aninactive status.

A broadcasting signal may be transmitted with a set of beams in a period(e.g., periodicity may be N TTIs) and the number of time or frequencyresources used for the broadcasting signal may be determined based onthe number of beams in the set (e.g., the same as the number of beams inthe set). For example, if M beams are used in the set, then M timeresources may be used for a beam sweeping.

A time/frequency resource associated with a beam may be predefined orconfigured in a period. Examples of a time/frequency resource associatedwith a beam being predefined or configured in a period are describedbelow.

A time/frequency resource associated with an inactive beam may be usedfor other signal transmissions. For example, a WTRU may attempt toreceive or monitor a downlink signal (e.g., control channel, referencesignal, and/or data channel) in a time/frequency resource associatedwith inactive beam while the WTRU attempts to receive or monitor abroadcasting signal in the time/frequency resource associated with anactive beam.

A WTRU may receive an indication of a beam state for a time/frequencyresource associated with a beam, wherein the indication may beimplicitly or explicitly signaled. For example, a WTRU may receive anindication of a beam state based on the reference signal used ortransmitted in the time/frequency resource. If a WTRU received a firsttype of reference signal, then the beam state is active. If the WTRUreceived a second type of reference signal, then the beam state isinactive. The first type and second type of reference signal may bedetermined based on at least one of a reference signal pattern, ascrambling sequence, a scrambling sequence ID, and the like.

A time/frequency resource associated with a beam may be dynamicallydetermined. For example, a time/frequency resource may be preconfiguredor predefined in a period and an associated beam for the time/frequencyresource may be dynamically determined based on the set of beams usedfor beam sweeping in the period. Examples of a time/frequency resourceassociated with a beam being dynamically determined are described below.

A WTRU may be indicated the set of beams used in a period. For example,if M beams are used in the period, then the WTRU may be indicated withthe number of beams in the set and which beams are in the set. A bitmapmay be signaled to indicate which beams are active beams. Consecutivetime resources may be used for beam sweeping and the number ofconsecutive time resources may be determined based on the number ofactive beams. A WTRU may receive or attempt to decode a broadcastingsignal when the associated beam is active. Otherwise, the WTRU may skipreceiving a broadcasting signal in a period.

All beams may be in an active state in an initial beam state, whereinthe initial beam state may be reset every N transmission time intervals(TTIs). The initial beam state may assume all beams are in active statewhere the initial beam state may be reset every X TTIs. Between resets,the beam state may remain the same.

A gNB may transmit beams in the active state in each period for abroadcasting signal and the gNB may turn-off beams in the inactive stateor use for other purpose. A New Radio physical downlink control channel(NR-PDCCH) with New Radio system information radio network temporaryidentifier (NR-SI-RNTI) may be used to schedule a New Radio physicaldownlink shared channel (NR-PDSCH for the beams in the active state.

Hereafter, a broadcasting signal may include any one or a combination ofa master information block (MIB), one or more of system informationblocks (SIBs), a cell-ID, and/or the like.

A selective beam sweep may continue to transmit system information basedon the same determined beam state until next reset of beam state. Duringa beam state reset, the beam state may change for a next cycle. A beamstate reset may occur first and may be followed by a reporting periodwhich is then followed by one or multiple selective beam sweep periods.

FIG. 2 shows a flow chart diagram of a selective beam sweeping basedsystem information transmission. As shown in the diagram 200, a gNBperforms initialization or a beam state reset 210. One or more WTRUsthen respond to the beams 220 transmitted from the gNB and the gNBobtains beam state information associated with the beams 230. Aselective beam sweep is performed by the gNB to transmit systeminformation based on the beam state 240. The gNB continues the selectivebeam sweep to transmit system information based on the beam state 250.The gNB then resets the beam state 260.

FIG. 3 shows a flow chart diagram of a selective beam sweeping basedsystem information transmission using an updated beam state. As shown inthe diagram 300, a gNB performs initialization or a beam state reset310. One or more WTRUs then respond to the beams 320 transmitted fromthe gNB and the gNB obtains beam state information associated with thebeams 330. The gNB performs a selective beam sweep to transmit systeminformation based on the beam state 340. Next, the WTRU sends a requestsignal to request beams from gNB 350 and the gNB updates the beam stateat gNB 360. A selective beam sweep is performed by the gNB to transmitsystem information based on the updated beam state at gNB 370. The gNBthen resets the beam state 380.

FIG. 4 is a beam state transition table that shows the states of a beamwhen using selective beam sweeping. In an example, the beam isestablished between a gNB and a WTRU. As shown in the state transitiontable 400, a beam in the inactive state may transition to the activestate again if the gNB receives an acknowledgement (ACK) from the WTRU.A beam in the inactive state remains in the inactive state if the gNBreceives a discontinuous transmission (DTX) indication (hereinafter,DTX) from the WTRU. A beam in the active state may transition to theinactive state in response to a DTX. A beam in the active state remainsin the active state in response to an ACK from the WTRU.

In an embodiment, NR systems may use a selective beam sweeping with anaperiodic broadcasting signal. A WTRU may measure one or more signals(e.g., always-on signals such as synchronization signals (e.g., primaryand secondary synchronization sequence (PSS and SSS)), a PBCH, abeam-specific reference signal (BRS), always-on SIBs, and the like)associated with one or more beams and the WTRU may determine at leastone beam to indicate to a gNB or a transmission reception point (TRP).

For example, a WTRU may measure downlink signals (e.g., beam-specificreference signals or BRSs) associated with one or more beams and theWTRU may determine at least one of the beams to indicate to a gNB. TheWTRU may then send or report an indication related to the determinedbeam and/or required broadcasting information in a certain time location(e.g., subframe n) and the WTRU may start monitoring a downlink controlchannel for information (e.g., downlink control information (DCI))within a time window, wherein the time window may be determined,configured, or indicated.

A DCI scrambled with an RNTI for a broadcasting signal (e.g., SI-RNTI)may be monitored in a downlink control channel search space within atime window when there is selective beam sweeping with an aperiodicbroadcasting signal. It is noted that any one or a combination of thefollowing may apply.

A DCI scrambled with a RNTI for broadcasting signal (e.g., SI-RNTI) maybe monitored in a downlink control channel search space within a timewindow.

The time window may start from subframe n+k and finish in subframe n+k+swhen a WTRU transmits a request indication (or REQ) of beam and/orbroadcasting signal in subframe n.

A downlink control channel search space may be a common search spacewhich may be common for all downlink beams or beam-specific searchspace. For example, one or more beam-specific search spaces may be usedand a WTRU may monitor a beam-specific search space which may beassociated with the beam indicated or determined for a broadcastingsignaling.

The DCI may include beam-related information (e.g., beam-ID),broadcasting signal type (e.g., MIB, SIB, SIB-x), a set of broadcastingsignals (e.g., one or more of SIBs), and/or period of broadcastingsignal transmission (e.g., 50 TTIs).

The DCI may include scheduling of a PDSCH which may carry one or morebroadcasting signals.

The DCI may include a valueTag that indicates the broadcasting signalchange status.

A WTRU may monitor the DCI in a common search space if the WTRU is inRRC idle while the WTRU may monitor the DCI in a WTRU-specific searchspace if the WTRU is in RRC connected.

A DCI without PDSCH scheduling information may carry broadcastinginformation and its search space (or DL control channel candidate) maybe beam-specific when there is selective beam sweeping with an aperiodicbroadcasting signal. It is noted that any one or a combination of thefollowing may apply.

One or more DL control channel search spaces may be configured and eachDL control channel may be associated with a beam. A WTRU may monitorbeam-specific search space within a time window for a broadcastingsignal reception.

One or more DL channel candidates may be used and a subset of DL controlchannel candidates may be associated with a beam. A WTRU may monitor asubset of DL control channel candidates which may be associated with thebeam the WTRU reported or indicated.

In another embodiment, a selective beam sweeping may be used with aperiodic broadcasting signal for a first set of SIBs and an aperiodicbroadcasting signal for a second set of SIBs. For example, a higherpriority SIBs (e.g., SIB-1/2) may be transmitted periodically with aselective beam sweeping and a lower priority SIBs (e.g., SIBs other thanSIB-1/2) may be transmitted aperiodically with a selective beamsweeping.

A selective beam sweeping for a higher priority SIBs (or a first set ofSIBs) may be periodically transmitted and the set of beams for theselective beam sweeping in each period may be determined dynamicallywhile a selective beam sweeping for a lower priority SIBs (or a secondset of SIBs) may be aperiodically transmitted and a WTRU may monitorassociated DCI during a time window in a beam-specific search space (orDL control candidates). For example, a higher priority SIB may be a MIBand a lower priority SIB may be other SIBs.

In an embodiment, a WTRU may indicate, report, or request a preferred,selected, or determined beam for reception of a broadcasting signal. AWTRU may measure one or more downlink signals for a measurement of abeam quality, a signal strength, a preferred beam, and/or a preferredset of beams and the WTRU may report, request, provide feedback, orindicate one or more beams (e.g., one or more preferred beams or one ormore determined beams). The WTRU may then attempt to receive abroadcasting signal based on the one or more beams reported, orindicated. It is noted that any one or a combination of the followingmay apply.

A WTRU may report a request bit or an indication bit which may bereferred to as a beam request signal (or REQ). The terms a beam requestsignal, feedback, ACK for beam, a beam indication signal, and a beamrequest indication may be used interchangeably. The beam request signalmay be transmitted to a gNB in a common channel or a dedicated channel.

A beam request signal, ACK for beam, a beam indication signal, or a beamrequest indication reporting may be based on energy or power level ofdownlink signal associated with a beam. A WTRU may measure a downlinksignal associated with a beam and the WTRU may report an ACK for thebeam that is above a predefined or predetermined threshold. Otherwise,the WTRU may not send an ACK for the beam (e.g., DTX).

The downlink signal associated with a beam may be at least one of a BRS,a subset of broadcasting signal (e.g., MIB), an essential part ofbroadcasting signal (e.g., SIB-1), or the like.

When a beam is ACKed, the beam is in an active state which may implythat there is a WTRU residing in the beam, otherwise the beam is in aninactive state. The selective beam sweeping may be performed only onthose beams in the active state.

DTX may imply that a WTRU may be not present in the beam or that theWTRU is out of the coverage of the beam.

A beam may be in the active state if an ACK is received by the gNB or ifan ACK is transmitted by the WTRU. A beam may be in the inactive stateif a DTX is detected by the gNB or no ACK is signaled by the WTRU.

In another embodiment, a first part of a broadcasting signal may betransmitted periodically with full beam sweeping and a second part ofthe broadcasting signal may be transmitted on-demand with selective beamsweeping. A WTRU may report beam request indication based on thereception of the first part of the broadcasting signal to activate thebeam associated with the second part of the broadcasting signal. It isnoted that any one or a combination of the following may apply.

A first part of a broadcasting signal may include at least one of a MIB,a SIB1, and a SIB2.

A second part of the broadcasting signal may include all SIBs other thanthe SIBs in the first part of the broadcasting signal.

A WTRU may receive a first part of a broadcasting signal with all beamswhich may be swept in each period. The WTRU may assume that the samebroadcasting signal is repetitively transmitted in all beams swept inthe period, and the WTRU may combine the received signals from one ormore beams at the receiver.

During the reception of the first part of a broadcasting signal, a WTRUmay determine one or more beams (or one or more preferred beams) for thesecond part of the broadcasting signal and the WTRU may report thedetermined beam or beams and/or request the second part of thebroadcasting signal, wherein the second part of the broadcasting signalmay include a set of SIBs or one or more subsequent SIBs.

A first part of a broadcasting signal may include any one or acombination of the following information: a number of beams used for thebroadcasting signal (e.g., single beam or multiple beams); uplinkresources to use for a determined beam indication (or reporting) and/ora request of a second part of the broadcasting signal; and atime/frequency resource configuration or allocation for the second partof the broadcasting signal. It is noted that any one or a combination ofthe following may apply.

Separate uplink resources may be configured for one or more SIBs in thesecond part of the broadcasting signal.

One or more groups may be configured or used for the second part of thebroadcasting signal and each group may have an associated uplinkresource to indicate. For example, if two groups of broadcasting signalare used, the first group (e.g., SIB-3˜SIB-7) may have its associateduplink resource and the second group (e.g., SIB-7˜SIB-12) may haveanother uplink resource to indicate.

The time/frequency resource may be configured separately for each beamin the second part of the broadcasting signal.

The periodicity of the first part of the broadcasting signal may beindicated from a synchronization signal.

In another embodiment, a WTRU may receive, attempt to receive, ormonitor a downlink signal which may indicate a transmission ofbroadcasting signal in a certain beam. The terms a downlink signal thatindicates a transmission of broadcasting signal in a certain beam, abeam activation signal, a beam activation indication, a confirmation ofACK indication, and an ACK-to-ACK signal may be interchangeably. It isnoted that any one or a combination of the following may apply.

One or more downlink signals may be reserved in a predefinedtime/frequency resource or a preconfigured control channel resource andthe one or more downlink signals may be used for a beam activationindication. For example, one or more downlink signals may be associatedwith one or more beam request indications and a gNB may use anassociated downlink signal for beam activation indication if the gNBreceived beam request indication.

The number of beam activation indication resources may be determinedbased on the number of beam request indication resources. For example,the number of beam activation indication resources may be the same asthe number of beam request indication resources. A WTRU may receive,attempt to receive, or monitor an associated beam activation resourceafter sending or transmitting a beam request indication. A beamactivation indication may be signaled via at least one of a higher layersignaling, a DCI, and a HARQ-ACK resource for an uplink signal (e.g.,PHICH).

A WTRU may determine a beam active status based on a signal strength ofa certain time/frequency resource. For example, if a received signalstrength of a first time/frequency/sequence resource is higher than apredefined threshold, a WTRU may assume that the associated beam isactive. Otherwise, the WTRU may assume that the associated beam isinactive. It is also noted that one or more time/frequency/sequenceresources may be preconfigured for one or more beams used, and a WTRUmay detect or monitor the received signal strength for the preconfiguredresources to determine the beam activation status.

A common control channel may be used to indicate a set of beams whichmay be active for a time period.

The WTRU uses the downlink signal in order to minimize the number ofbeams used to transmit the always-on signal for the beam sweep.Accordingly, WTRU direction information may be needed, an energy-basedACK reporting scheme may be implemented, and selective beam sweeping maybe used.

The direction information or beam information of a WTRU may need to beknown in order to enable selective beam sweep for system information. AnACK reporting scheme may be implemented in order to determine thedirection information or beam information of a WTRU. The ACK reportingscheme may be based on an energy or power level. The energy of powerlevel may be measured via a BRS or the like. For example, when a WTRUdetects energy for a beam that is above a predetermined threshold, theWTRU may report an ACK. Otherwise, the WTRU may report a DTX. Asdescribed above, a DTX may imply that a WTRU is not present in the beamor that the WTRU is out of the coverage of the beam.

When the WTRU reports an ACK and the beam is ACKed, the beam the beamgoes to an active state indicating that there is a WTRU residing in thebeam. If the WTRU does not report an ACK and the beam is not ACKed, thebeam goes to an inactive state. As described above, selective beamsweeping is only performed on beams in the active state.

All beams are associated with a beam state. It is assumed that aninitial beam state for each beam is the active state. The state of abeam remains the same between resets. The initial beam state may bereset ever N TTIs. A beam state may be obtained during a reportingperiod. During the reporting period, a WTRU may report an ACK respondingto a beam if the energy or power measured in a BRS or the like for thebeam is above a predetermined threshold. The WTRU may measure one ormore signals (e.g., one or more always-on signals, such assynchronization (e.g., PSS, SSS), PBCH, BRS, always-on SIBs, and thelike) associated with one or more beams and the WTRU may determine atleast one beam to indicate to a gNB or a TRP. Otherwise, the WTRU mayreport a DTX.

A gNB or a TRP determines that a beam is in an active state if an ACK isreceived. The gNB or the TRP determines that a beam is in an inactivestate if a DTX is detected.

During a beam sweep period, a gNB or a TRP may transmit systeminformation in active beams. The gNB or the TRP may also turn off beamsfor inactive beams during the beam sweep period.

Non-essential system information may be transmitted using abeam-specific common control channel. System information transmissionoverhead may be high using WTRU common signaling in all directions andall beams due to the amount of beam sweeping that may be required tocover entire service areas. This transmission overhead may also causehigh latency or delay.

In an embodiment, a selective beam sweep is used to delivernon-essential system information according to direction information orbeam information of one or more WTRUs. Because one or more directions orbeams may not have a WTRU residing in the beam, only selective beams areused by a gNB or a TRP for sweeping to deliver non-essential systeminformation. For example, a NR-PDCCH with a NR-SI-RNTI may be used toschedule a NR-PDSCH for those beams. The system information may then betransmitted by the gNB or the TRP using a selective beam requesttransmission.

As described above, it is assumed that the initial beam state of allbeams is the active state. The initial beam state may be reset every NTTIs. Between resets, a beam state transition process may occur. Anenergy-based ACK reporting scheme may provide beam state transitions forbeams. Then, beam request sweeping may be performed accordingly.

During a reporting period, a WTRU may report an ACK responding to a beamif the energy or power measured in a BRS or the like for the beam isabove a predetermined threshold and the beam is in active state. Duringthe reporting period, the WTRU may report an ACK to request a beam ifthe beam is in inactive state. During a reporting period, the WTRU maymeasure on one or more signals (e.g., one or more always-on signals suchas synchronization (e.g., PSS, SSS), PBCH, BRS, always-on SIB, and thelike) associated with one or more beams and the WTRU may determine atleast one of the beams to indicate to a gNB or a TRP. Otherwise, theWTRU may report a DTX.

During a beam sweep period, the gNB or the TRP may maintain a beam inthe active state if at least one ACK is received from WTRUs in the beam.The gNB or the TRP may turn a beam into the active state if at least oneACK (as requested) is received from one or more WTRUs in the beam. ThegNB or the TRP may turn a beam into the inactive state if a DTX isdetected for all WTRUs in the beam.

A gNB or a TRP may use a single beam mode or a multiple beam mode for asystem information transmission. A WTRU may receive the beam mode (e.g.,single beam mode or multiple beam mode) before receiving the systeminformation (e.g., via synchronization signal and/or initialbroadcasting signal including a MIB).

In an embodiment, WTRU procedures for supporting on-demand systeminformation transmission may be determined based on a single beam modeor a multiple beam mode. There exists a need to turn a periodic systeminformation transmission into an aperiodic transmission via a request orrequest command (REQ) from a WTRU. A gBN or a TRP then transmits systeminformation in a system information transmission to the WTRU. The systeminformation transmission may also be referred to as a SIB transmission.If a WTRU correctly receives the system information, the systeminformation may not need to be transmitted again until a next requestfrom the WTRU.

For example, a WTRU may request system information via a common channel.A beam-specific common control may be used for system informationtransmission. Here, system information requested by a WTRU may also beshared with other WTRUs in the same beam. The beam may be a single beamor a beam in multi-beam system. In a single beam system, systeminformation requested by a WTRU may also be shared by other WTRUs in thesame TRP or cell in the single beam system. In a multi-beam system, thisis referred to as a beam-specific request method.

In another example, a WTRU may request system information via adedicated channel. A beam-specific dedicated control may be used for asystem information transmission. Here, system information requested by aWTRU may not be shared by other WTRUs.

The WTRU procedures for supporting on-demand system informationtransmission may also support a request-based and a cyclic redundancycheck (CRC)-based ACK reporting scheme.

When a single beam mode is used for a system information transmission, aWTRU may decode one or more SIBs in a SIB transmission (TX) opportunitytime symbol (or a SIB TX period). The WTRU may generate an ACK ifdetection of the one or more SIBs is successful; otherwise, the WTRUgenerates an NACK. The WTRU sends the ACK or NACK based on the detectionstatus. The WTRU may also send a DTX for a TRP or a cell may be turnedon/off and enter an inactive or active state.

When a multiple beam mode is used for a system information transmission,a WTRU may decode one or more SIBs in a SIB TX opportunity time symbol(or a SIB TX period) associated with a beam (e.g., a beam-specific SIBTX period). The WTRU may generate an ACK if detection of the one or moreSIBs in a beam is successful; otherwise, the WTRU may generate NACK. TheWTRU may send the ACK or NACK in a resource which may be associated withthe beam based on the detection status. The WTRU may also send a DTX fora beam or beams to be turned on/off and enter an inactive or activestate.

A gNB may stop transmitting system information (or system information ina specific beam) if an ACK is detected, and a WTRU may assume or it maybe indicated that the gNB stops transmitting system information (orsystem information in a specific beam).

A gNB may retransmit system information (or system information in aspecific beam) if an NACK is detected, and a WTRU may assume, expect, orattempt to receive the retransmission of system information (or systeminformation in a specific beam) if the WTRU send a NACK.

FIG. 5 is a beam state transition table that shows the states of a beambased on a data detection state. After an initial beam state is set, abeam state transition may occur if a gNB receives a SIB request from aWTRU. A beam transition may also occur in response to a data detectionstate of a SIB for one or more WTRUs. The data detection state mayproduce an ACK or a NACK. The data detection state may be based on a CRCtest. The data detection state may be a pass or a fail.

As shown in FIG. 5, a beam in the inactive state may transition to theactive state again if a gNB receives a SIB request from a WTRU. A beamin the inactive state remains in the inactive state if a DTX isdetected. A beam in the active state may transition to the inactivestate due to a CRC-based ACK. A beam in the active state may transitionto the inactive state if a DTX is detected. A beam in the active statemay remain in the active state due to a CRC-based NACK.

FIG. 6 is a beam state transition table that shows the states of a beambased on based on a data detection state and energy. As shown in FIG. 6,a beam in the inactive state may transition to the active state if a gNBreceives a SIB request from a WTRU. A beam in the inactive state remainsin the inactive state if a DTX is detected. A beam in the active statemay transition to the inactive state due to energy falling below apredetermined threshold. For example, a beam in the active state maytransition to the inactive state due to WTRU DTX for the measured poweror due to signal strength on a BRS (or the like) is lower than apredetermined threshold. A base in the active state may transition tothe inactive state due to a CRC-based ACK (ACK_D) or if a DTX isdetected. A beam in the active state may remain in the active state dueto a CRC-based NACK (NACK_D) or an energy based ACK (ACK_E).

FIG. 7 shows a flow chart diagram of a selective beam sweeping basedsystem information transmission based on a data detection state andenergy of a WTRU. As shown in the diagram 700, a gNB performsinitialization or a beam state reset 710. One or more WTRUs then respondto the beams transmitted from the gNB 720 and the gNB obtains beam stateinformation associated with the beams 730. The gNB performs a selectivebeam sweep to transmit system information based on the beam state 740.The one or more WTRUs then respond to the beams transmitted from the gNBbased on a data detection state of system information of the one or moreWTRUs 750. Next, the one or more WTRUs sends a request signal to requestbeams to be transmitted from the gNB 760 and the gNB updates the beamstate 770 based on the one or more request signals received from the oneor more WTRUs. A selective beam sweep is performed by the gNB totransmit system information based on the updated beam state 780. The gNBthen resets the beam state 790.

For a beam state transition based on energy, a DTX being detectedimplies that the WTRU is not present. For a beam state transition basedon a data detection state and energy, a DTX being detected implies thatthe WTRU is not present or that the WTRU is present but did not requesta SIB transmission or system information in the beam.

As described above, a WTRU may send an ACK to acknowledge the receipt ofa SIB transmission. For example, if a gNB receives an ACK in a beam, itimplies that there is at least one WTRU in that beam. If an ACK is notreceived, a gNB may assume that there is no WTRU in the beam and aselective beam sweep may exclude that beam from a beam sweep.

FIG. 8 shows a timing diagram of ACK to SIB process used for SIBtransmissions. As shown in FIG. 8, a WTRU receives and measure one ormore DL synchronization signals, a PBCH, and a SIB transmission. TheWTRU may then send an ACK in response to a SIB transmission.

An energy-based ACK to a SIB transmission may be used to build thedirectional profile of a WTRU during an initial state. During a beamstate transition, sending an ACK to a SIB transmission may be used totrack the directional profile of a WTRU. For example, if a CRC-based ACKis received, then the one or more beams participating in the beam sweepmay stop the SIB transmission. The beam may change from the active beamstate to an inactive beam state in the next beam sweep. If at least oneNACK is received, then the SIB transmission is sent again for that beam.If a beam becomes silent and a DTX is detected due to no WTRU beingpresent in the beam, the active beam may transition to the inactivestate for the next beam sweep.

For those beams not participating in the beam sweep, if a REQ isreceived, the gNB starts sending a SIB transmission again. Therefore, anACK and a DTX may transition a beam in the active state to the inactivestate. A NACK may keep a beam in the active state still active. While aREQ may transition a beam in the inactive state to the active state fora next beam sweep. A gNB may receive any one or a combination of an ACK,NACK, DTX, and REQ in a corresponding time symbol for a beam.

In an embodiment, WTRU procedures supporting a beam-specific request fora SIB transmission are used to minimize an always-on signal. In abeam-specific request for a SIB transmission, a WTRU may request a SIBor SIBs via the beam in which the WTRU resides. When a WTRU requires aSIB or SIBs, the WTRU may perform non-autonomous HARQ processes for theSIB or SIBs to initiate a request for a SIB transmission.

In an embodiment, a WTRU may use non-autonomous HARQ processes torequest a SIB transmission. FIG. 9 shows a timing diagram of an examplenon-autonomous HARQ process used for SIB transmissions. In FIG. 9, a SIBtransmission may first be transmitted in all directions and in all beams(e.g., beams 1, 2, 3 . . . M) at time symbols 1, 2, 3 . . . M,respectively. When a WTRU detects a SIB transmission, the WTRU mayreport an ACK to a gNB. One or more WTRUs may try to detect a SIBtransmission in all beams and in all directions. It is noted that WTRUsin different beams may report ACKs back to the gNB. When an ACK isreceived by the gNB or a TRP, the SIB transmission may be stoppedbecause the one or more WTRUs may have already received the systeminformation. FIG. 9 shows that beams 1, 2, 3 . . . M are all ACKed in anext transmission time opportunity. All beams may not transmit a SIBtransmission or SIBs.

A WTRU may request a SIB transmission when needed. The WTRU may send aREQ to a gNB or a TRP for a beam that corresponds with the location ofthe WTRU. As shown in FIG. 9, one or more WTRUs may send a REQ for a SIBto a gNB for beams 1 and 3. The gNB then receives the REQs from theWTRUs and the SIB is transmitted in the corresponding beams (i.e., beams1 and 3) in a next transmission opportunity.

FIG. 10 shows a timing diagram of another example non-autonomous HARQprocess used for requesting SIB transmissions. In FIG. 10, a SIBtransmission is first transmitted in all directions and in all beams(e.g., beams 1, 2, 3 . . . M) at time symbols 1, 2, 3 . . . M,respectively. When a WTRU detects a SIB transmission, the WTRU mayreport an ACK to a gNB. One or more WTRUs may detect a SIB transmissionin all beams and all directions. WTRUs in different beams may reportACKs back to the gNB. For those beams that have been ACKed, the gNB orthe TRP may stop the SIB transmission because the one or more WTRUs mayhave already received the system information. When a WTRU does notdetect a SIB transmission for a certain beam, the WTRU may either NACKor DTX for that beam and the SIB transmission may continue in that beambecause the one or more WTRUs may have not received the systeminformation. A WTRU may request a SIB transmission when needed.

In an embodiment, a WTRU may use a combined CRC-based and energy-basedmethod for performing non-autonomous HARQ processes to request a SIBtransmission. In this embodiment, energy or power may be measured via abeam-specific reference signal (BRS). If detected energy is above apredetermined threshold but a CRC test does not pass, a WTRU may reporta NACK. The NACK may provide an indication that the detected energy ofone or more beams is above a predetermined threshold but a CRC test doesnot pass for one or more beams. Accordingly, a gNB may then retransmitthe SIB transmission or system information. A NACK used in this mannermay be referred to as an intelligent NACK. A WTRU may report a DTX ifdetected energy is below a predetermined threshold. A DTX may alsoindicate that there is not a WTRU residing in a beam. A WTRU may reportan ACK if detected energy is above a predetermined threshold and CRCpasses.

In an embodiment, a WTRU may use an energy-based method for performingnon-autonomous HARQ processes to request a SIB transmission. Similar tothe embodiment described above, energy or power may be measured via aBRS. If detected energy is above a predetermined threshold, a WTRU mayreport an ACK. A WTRU may report a DTX if detected energy is below apredetermined threshold.

In FIG. 10, beam 1 is ACKed in a next transmission time opportunity.FIG. 10 also shows that one or more WTRUs do not detect a SIBtransmission for beams 2 and M. The one or more WTRUs then report anNACK for beams 2 and M. The SIB transmission continues in beams 2 and Msince the one or more WTRUs may have not received the systeminformation. For beam 3, the one or more WTRUs do not detect a SIBtransmission for beam 3 and the one or more WTRUs may report a DTX forbeam 3. Alternatively, the gNB or the TRP may continue transmitting theSIB transmission for a preset timer before stopping transmission of theSIB. As a result, the gNB or the TRP may continue the SIB transmissionin beams 2 and M but the SIB transmission is stopped in beam 3.

In a next uplink time opportunity, a WTRU may request system informationwhen needed. The WTRU may send a REQ to the gNB for the correspondingbeam in which it resides. As shown in FIG. 10, one or more WTRUs maysend REQs to the gNB via beams 1 and 3. When the gNB receives theserequests or REQs from the one or more WTRUs, SIB transmission are madein the corresponding beams (i.e., beams 1 and 3) in a next SIBtransmission time opportunity. In FIG. 10, because beam 2 has beenACKed, a SIB may not be transmitted in a next SIB transmission timeopportunity. Beam M has been NACKed and a SIB may be transmitted againin beam M in a next SIB transmission time opportunity. As a result, thegNB or the TRP may continue the SIB transmission in beams 1 and 3 due toa request from the one or more WTRUs and continue the SIB transmissionin beam M due to beam M having been NACKed. The gNB or the TRP may stopthe SIB transmission in beam 2 due to beam 2 having been ACKed.

A timer may be set for a SIB transmission when a gNB detects a DTXbecause a DTX may imply that there is no WTRU in the beam. A NACKresponse may imply SIB is not received correctly but there is a WTRU inthat beam. A timer may also be set for SIB when a gNB detects a NACKresponse. Since energy may be above the threshold but data cannot bedecoded correctly, it may imply that there is no WTRU is residing in thebeam and the energy may come from interference or noise. If the timerexpires, the gNB may stop the SIB transmission.

When a gNB receives feedback from a WTRU for a given beam, the gNB mayreceive all ACKs from all WTRUs in the beam. The gNB may stop a SIBtransmission. When the gNB receives at least one NACK response from aWTRU in that beam, the gNB may continue to a SIB transmission since someof WTRUs may not receive the SIB transmission.

As described above, the WTRU may send an ACK to indicate a WTRU beamlocation. In an embodiment, the ACK may carry information in addition toacknowledging the beam location of the WTRU. The information carried inthe ACK may be used to request a next SIB transmission. Moreparticularly, the WTRU may send an ACK to indicate whether one or moreSIBs should be transmitted next time based on a WTRU request. The ACKsent from the WTRU may also indicate how many SIBs should be transmittednext time based on a WTRU request. The WTRU may also indicate the timeduration before SIBs should be transmitted next time.

A next SIB transmission may be requested using an ACK after L timeintervals of SIB transmissions for a given beam. A BPSK modulated ACKmay carry 1 bit to indicate L time intervals of SIB transmissions. Forexample, L may be L={1, 4} or L={1, 8}. It is noted that other valuesets for L are possible. A QPSK modulated ACK may carry 2 bits toindicate L time intervals of SIB transmissions. For example, L may beL={1, 2, 3, 4} or L={2, 4, 6, 8}. It is noted that other value set for Lmay be possible.

FIG. 11 shows a timing diagram of an example of an ACK that is used torequest a next SIB transmission. As shown in FIG. 11, an ACK may be usedto request a next SIB transmission during HARQ processing. In FIG. 11, aSIB transmission is first transmitted in all directions and in all beams(i.e., beams 1, 2, 3, . . . , M) at time symbols 1, 2, 3 . . . M,respectively. When WTRUs are present in all beams, a gNB may receiveACKs for all beams. The WTRU may use an ACK which may carry additionalrequest information to request a next SIB transmission for WTRU toreceive an additional SIB.

FIG. 12 shows a flow chart diagram of an example of method for use in agNB and one or more WTRUs for signaling system information in order toenable efficient beam sweeping.

As described above and in diagram 1200, a gNB transmits a broadcastsignal including system information 1210. The broadcast signal may betransmitted in one or more directional beams. The broadcast signal maybe an always-on signal. The broadcast signal may be transmitted over aPBCH or a similar channel. The broadcast signal may also be transmittedover a channel carrying remaining minimum system information. The systeminformation included in the broadcast signal may provide configurationinformation, which includes any one or a combination of a resourceallocation, mapping information, a resource indication, and a modeindication directing the behavior of the WTRU. The configurationinformation may include an indication regarding whether the WTRU is ableto transmit any one or a combination of a request signal, a feedbacksignal, or neither to the gNB. The configuration information may allowthe WTRU to provide feedback associated with the system information. Theconfiguration information may be part of RACH configuration or differentfrom RACH configuration. The configuration information may be carried orincluded in broadcast signal or channel, such as a synchronizationsignal (SS), remaining minimum system information (RMSI), a NR-PBCH, orother system information (OSI). The system information may be referredto as first system information or remaining minimum system information.

A WTRU receives the system information in the broadcast signal anddetermines whether the received system information satisfies receptioncriteria 1220. The reception criteria may include any one or acombination of the following: the WTRU successfully receiving a CRC ofthe system information or the WTRU determining that the energy of a beamis above a threshold.

The WTRU determines configuration information using the broadcast signalin order to provide feedback associated with the system informationincluded in the one or more directional beams 1230. The WTRU thentransmits a signal on the one or more beams using the configurationinformation associated with the received system information 1240. Thetransmitted signal may be a feedback signal that provides feedbackassociated with the system information included in the one or moredirectional beams. The feedback may be transmitted for each of the oneor more directional beams. The feedback provided in the transmittedsignal may include any one or a combination of beam informationassociated with the WTRU and an indication regarding whether thereceived system information satisfies reception criteria.

The gNB receives the signal from the WTRU for each of the one or moredirectional beams 1250 and the gNB then sets a beam state for a systeminformation transmission based on the feedback included in thetransmitted signal 1260. The beam state may be an active state or aninactive state.

The gNB then performs a selective beam sweep to transmit the systeminformation 1270. The selective beam sweep to transmit the systeminformation may be based on any one or a combination of the feedbackincluded in the transmitted signal and the beam state. The transmittedsystem information may be referred to as second system information orother system information transmissions (SIBs).

In an embodiment, a feedback signal (e.g., ACK and DTX) for an initialbeam state may use a fixed preamble sequence. For example, an ACK isgenerated by a WTRU if such a preamble is detected. Otherwise, a DTX isdetected.

In an embodiment, a feedback signal (e.g., ACK and NACK) for a beamstate transition uses fixed preamble sequences. Three fixed preamblesequences may be used for an ACK, a NACK, and a REQ. For example, when aWTRU reports an ACK, the WTRU may transmit preamble sequence 1. When aWTRU reports an NACK, the WTRU may transmit preamble sequence 2. When aWTRU sends a REQ, the WTRU may transmit preamble sequence 3. Otherwise,a DTX is detected.

When a gNB receives the corresponding preamble sequence, the gNB mayknow whether to transmit a SIB. For example, if the gNB receives onlypreamble sequence 1 for a given beam, the gNB may stop a SIBtransmission for that beam. If the gNB receives preamble sequence 2 orpreamble sequence 3, the gNB may continue or start the SIB transmissionfor that beam.

In an embodiment, a feedback signal for a beam state transition usespreamble groups. Three fixed preamble groups may be used for an ACK, aNACK and a REQ. For example, when a WTRU reports an ACK, the WTRU maytransmit preamble group 1. When a WTRU reports an NACK, the WTRU maytransmit preamble group 2. When a WTRU sends a request command (REQ),the WTRU may transmit preamble group 3. Otherwise, a DTX is detected.

When a WTRU reports an ACK, the WTRU may select a preamble sequence frompreamble group 1. When a WTRU reports an NACK, the WTRU may select apreamble sequence from preamble group 2. When a WTRU sends a REQ, theWTRU may select a preamble sequence from preamble group 3.

In an embodiment, a feedback signal for a beam state transition usesreduced preamble sequences where two preamble sequences are used for ACKand REQ. For example, when a WTRU reports an ACK, the WTRU may transmitpreamble sequence 1. When a WTRU sends a REQ, the WTRU may transmitpreamble sequence 2. Otherwise, a DTX is detected.

When a WTRU reports an ACK, the WTRU may transmit preamble sequence 1.When a WTRU sends a REQ, the WTRU may transmit preamble sequence 2.

When a gNB receives the corresponding preamble sequence, the gNB mayknow whether to transmit a SIB. For example, if a gNB receives only apreamble sequence 1 for a given beam, the gNB may stop the SIBtransmission for that beam. If a gNB receives a preamble sequence 2, thegNB may continue the transmission of SIB for that beam regardless ofwhether it receives preamble 1 or not. If at least one WTRU in a givenbeam requests a SIB, the gNB may transmit a SIB in that beam. The WTRUsin that beam that already received the SIB may not be required to decodethe SIB.

In an embodiment, a feedback signal for a beam state transition usesreduced preamble sequences where two preamble sequences are used for anACK, a NACK, and a REQ. For example, when a WTRU reports an ACK, theWTRU may transmit preamble sequence 1. When a WTRU reports an ACK orsends a REQ, the WTRU may transmit preamble sequence 2. Because a NACKis used for the active state and a REQ is used for the inactive state,there is no ambiguity. Otherwise, a DTX is detected. This embodiment mayreduce the number of preambles used.

When a gNB receives a corresponding preamble sequence, the gNB maydetermine whether to transmit a SIB. For example, if a gNB receives onlya preamble sequence 1 for a given beam, the gNB may stop a SIBtransmission for that beam. If the gNB receives a preamble sequence 2,the gNB may continue or start the transmission of SIB for that beamregardless of whether it receives preamble 1 or not. If at least oneWTRU in a given beam requests a SIB, the gNB may transmit a SIB in thatbeam. The WTRUs in that beam that already received the SIB may not berequired to decode the SIB.

When a beam is active, a WTRU may send an ACK or a NACK using preamblesequence 1 or preamble sequence 2. When a beam is inactive, a WTRU maysend a REQ to request a SIB transmission. Since the NACK and the REQ usein two different beam states, the NACK and the REQ they do not overlap.Alternatively, in the active state, a WTRU may send a NACK or REQ.However, it is not necessary for a WTRU to request the same SIB sincethe SIB has been transmitted due to other WTRUs. If a WTRU alreadyrequested the same SIB, this same SIB may be shared and received by allWTRUs residing in the same beam.

It may be possible for WTRUs to expect different SIBs. In this case,even in an active state, a gNB may send different SIBs based on a WTRUrequest command. For example, there may be some SIBs are always on, someSIBs are on-demand before a RACH procedure and some SIBs are on-demandafter a RACH procedure. Each ACK may be time and beam synchronous witheach SIB. For example, any one or a combination of the following mayoccur: a MIB is always on; SIB1/SIB2 are on-demand at a beam level (eachbeam may serve multiple WTRUs) and may be performed before and after aRACH; SIB3-SIB20 are on demand at a WTRU level and always after a RACH.

The use of on-demand may not always beneficial because common controlinformation is duplicated for each WTRU. However, when the number ofWTRUs is small, the use of on-demand may be advantageous. A switchbetween always-on and on-demand may be used depending on the number ofWTRUs in a TRP or a cell.

In LTE, multiple types of system information are contained in differentSIBs, and these SIBs may be sent using different resources. In NR,multiple SIBs may be processed jointly before their transmissions. Forexample, a gNB may simultaneously broadcast multiple SIBs jointly. Inanother example, a WTRU may request several SIBs or all SIBs, and a gNBmay transmit the requested SIBs to the WTRU in one shot.

In NR, the channel coding of these SIBs may be based on Polar codes.There are two rate matching schemes for Polar codes to achieve adesirable coded block size. A first scheme is based on the puncturing ofa large sized Polar code. A second scheme is based on the combination ofmultiple smaller sized Polar codes. A flexible Polar encoding scheme mayswitch between these two schemes, based on the number of SIBs to bejointly encoded and the coding rate associated with the SIBs. Theflexible Polar encoding scheme is needed in order to support theencoding of variable number of SIBs with their associated coding rate.

When there is joint processing of multiple SIBs, each component SIB mayhave different priorities. For example, SIB1 may be more important thanother SIBs and it should be of highest priority. In general, SIB_X ismore important than SIB_Y, if X<Y. Hence, SIB_X should be of higherpriority than SIB_Y. However, this condition may not be always true. Inthe case on-demand SIBs (i.e., a WTRU requests to get several SIBs froma gNB), a WTRU may provide the priority order of its required SIBs.

It is known that Polar codes have different reliability levels of itsbit channels. When these reliability levels are associated with thepriority orders of the SIBs, then a higher priority SIB may besuccessfully decoded with a higher probability. This associationdecision could also be incorporated in the flexible Polar encodingscheme.

In an embodiment, a NB dynamically determines the Polar encoding schemefor SIBs. FIG. 13 shows a flow chart diagram of an example of a methodfor use in a gNB to dynamically determine the Polar encoding scheme forSIBs.

As shown in the diagram 1300, in response to the gNB having multipleSIBs to broadcast, or the gNB receives an on-demand SIB request, the gNBdecides to jointly encode multiple SIBs 1310. Next, the gNB decides tojointly encode the multiple SIBs 1320. The gNB first calculates theoverall information block size of these SIBs and its associated codingrate. This information is used to fix a target coded block size.

Based on the number of coded block bits and the coding rate, the gNBdecides on a rate matching scheme 1330. The gNB needs to determinewhether it will use a single Polar code with some puncturing or whetherit will combine multiple Polar codes to achieve the target coded blocksize.

For a single Polar code application, the gNB determines the priorityorder of the jointly encoded SIBs 1340 and then the gNB maps the SIBs tothe different input bit channels of the Polar code based on the prioritylevels of these SIBs 1350. The gNB knows the priority order of thejointly encoded SIBs either by default (i.e., SIB_X>SIB_Y, for X<Y) orby the SIB request messages from a WTRU.

For a multiple Polar codes application, the gNB determines the priorityorder of the jointly encoded SIBs 1360 and then the gNB maps the SIBs tothe input bit channels of multiple Polar codes 1370. First, the gNBaligns bit channel reliability levels among different component Polarcodes. Then, the gNB maps the SIBs to the different input bit channelsof these Polar codes based on the priority levels of these SIBs. SomeXOR operations of the SIB bits may be applied before the mapping.Specifically, some XORed bits will also be mapped to some input bitchannels of these polar codes. The gNB knows the priority order of thejointly encoded SIBs either by default or by the SIB request messagesfrom a WTRU.

The gNB then applies the Polar encoding process to the SIBs 1380.

FIG. 14 shows a diagram of an example of Polar mapping function thatmaps SIBs to the input bit channels of multiple Polar codes. Moreparticularly, FIG. 14 shows a detailed example of element 1370 found inFIG. 13. As shown in the diagram 1400, M SIBs X₁, . . . , X_(M) are tobe jointly encoded. It may be calculated from the information block sizeΣ_(i=1) ^(M) X_(i) and the desired coding rate R that the coded blocksize is

$\frac{\sum\limits_{i = 1}^{M}X_{i}}{R}\mspace{14mu} {{bits}.}$

In FIG. 14 the decision is made to use L Polar codes, with theirrespective block sizes n₁, . . . , n_(L) bits, since

$\frac{\sum\limits_{i = 1}^{M}X_{i}}{R} = {\sum\limits_{i = 1}^{L}{n_{i}.}}$

Because the priority order of the SIBs is known, the priority order ofthe input bits is also determined. Based on this information, the ajoint Polar mapping function designs a binary mapping matrix J of sizeΣ_(i=1) ^(M) X_(i) by Σ_(i=1) ^(L) n_(i). The output of the joint Polarmapping function may be calculated as:

[b_(1,1), . . . , b_(1,X) ₁ , b_(2,1), . . . , b_(2,X) ₂ , . . . ,b_(M,1), . . . , b_(M,X) _(M) ]·J

The design of J accounts for the priority levels and the sizes ofmultiple Polar codes.

FIG. 15 shows a flow chart diagram of an example of system informationtransmission and processing in a gNB. As shown in the diagram 1500, thegNB determines whether it has multiple SIBs to be broadcast 1510. ThegNB may also receive on-demand SIB request from one or more WTRUs 1520.The gNB determines a priority order for a system information payload1530.

A CRC may be attached to one or multiple SIBs when the one or multipleSIBs are transmitted simultaneously in the system information payload.Depending on the priority of the system information, the gNB may assigna CRC to each SIB or a CRC may be assigned to a category of SIBs 1540. Ahigh priority CRC may be assigned to a high priority SIB or SIB categorywhile a low priority CRC may be assigned to low priority SIB or SIBcategory. A priority of system information may be predefined or it maybe based on the need of a WTRU. A priority list for system informationmay be provided by a WTRU when the WTRU requests system information.

The gNB then concatenates the payload and CRC as a function of priorityorder 1550, maps different SIBs to the input bit channels of multiplePolar codes 1560, and encodes the payload and CRC 1570.

FIG. 16 shows a signaling diagram of an example message flow between agNB and multiple WTRUs for a SIB transmission. As shown in the diagram1600, the gNB may broadcast multiple SIBs simultaneously with theencoding of these SIBs based on a single or multiple polar codes 1610.The Polar encoding scheme selection may depend on the proceduresdescribed above in FIG. 13.

WTRU1 may send a SIB request message to the gNB 1620. WTRU1 may requestseveral SIBs with a priority order. For example, WTRU1 may request threeSIBs with the priority order of SIB_x>SIB_y>SIB_z . If priority orderinformation is not provided, then the gNB may assume that the SIBs arein a default priority order (i.e, SIB_x>SIB_y if x<y). The gNB selects aPolar encoding scheme based on the SIB request using the methoddescribed in FIG. 13. The gNB then sends the SIB response message toWTRU1 1630.

The gNB may also receive a SIB request from WTRU2 1640 and send a SIBresponse message to WTRU2 1650. The gNB may then also broadcast multipleSIBs simultaneously again 1660.

In an embodiment, a WTRU may request system information via commoncontrol channel. For example, a WTRU may request system information viaa SI-RNTI PDCCH/PDSCH and a schedule request (SR) or the like.

In another embodiment, a WTRU may request system information via adedicated channel. For example, a WTRU may request system informationvia a C-RNTI PDCCH/PDSCH and a dedicated UL control or the like.

There are two schemes that may be used for a WTRU-specific request for aSIB transmission.

According to a first scheme, predefined time locations are used for SIBtransmissions. The SIB may not be always transmitted. However, when aSIB is transmitted, the SIB is transmitted in the predefined timelocations. This may improve energy efficiency because all SIBs aretransmitted in the predefined time by request causing the beam energyfor the SIBs to be low.

In the first scheme, when a WTRU requests a SIB transmission, a gNB maytransmit the SIB based on the request from the WTRU. If the time whenthe WTRU requests the SIB is x time units ahead of SIB predefined timelocations, then the gNB may transmit the SIB in a next immediate SIBtransmission time location. Otherwise, the gNB may wait until a nextopportunity for the SIB transmission in following SIB predefined timelocations. The time unit of x may be an OFDM symbol, a time symbol, aTTI or the like. The value of x may depend on systems and designs andthe value of x may be configurable or predefined. For example, x may bea few OFDM symbols or one TTI. If a SIB time location is TTI#n, x may beTTI#n-k where k=1 or k>1. In this example, a common control channel maybe used and a SI-RNTI may be masked with a PDCCH to schedule the SIB viaa PDSCH.

FIG. 17 shows a flow chart diagram of using predefined time locationsfor SIB transmissions. As shown in the diagram 1700, a WTRU sends arequest to a gNB for system information 1710. The WTRU then waits for anext predefined time location to receive the requested systeminformation 1720. The system information is then obtained by the WTRU atthe predefined time location 1730.

In a second scheme, aperiodic time locations are used for SIBtransmissions. The aperiodic time locations are determined based on whena WTRU request a SIB transmission. This scheme may have higher energycost because SIBs may be transmitted anytime which may consume beamenergy if many WTRUs request SIBs at different times. This scheme doesnot have predefined time locations for SIB transmissions. The second maybe partial WTRU-specific (via SI-RNTI) or total WTRU-specific (viaC-RNTI).

In the second scheme, when a WTRU requests a SIB transmission, the gNBmay transmit the SIB based on the request from the WTRU. Because thesecond scheme does not have predefined time locations for SIBtransmissions, the gNB may transmit the SIB immediately without waitingfor a SIB transmission opportunity. The gNB may use a PDCCH masked withcell RNTI (C-RNTI) to schedule the SIB transmission for the WTRU.

FIG. 18 shows a flow chart diagram of using periodic time locations forSIB transmissions. As shown in the diagram 1800, a WTRU sends a requestto a gNB for system information 1810. The WTRU then waits for apredefined fixed or variable number of TTIs to receive the requestedsystem information 1820. The system information is then received by theWTRU at the predefined time location 1830.

The first scheme is partially WTRU-specific. The second scheme isWTRU-specific.

Although the first scheme is based on a WTRU-specific request for a SIBtransmission, a SI-RNTI is used. Therefore, other WTRUs may still beable to receive and decode a PDCCH using the SI-RNTI and decode a PDSCHfor the SIB transmission.

According to the first scheme, when a WTRU requires a SIB, the WTRU mayfirst try to decode SIB in predefined time locations. Different SIBs mayhave the same or different predefined time locations. The WTRU may waitfor those corresponding time locations to receive the SIB that itrequires. If the WTRU can decode the required SIB, the WTRU may notrequest a SIB. If the WTRU cannot decode the SIB, the WTRU may request aSIB if it is needed by WTRU.

The WTRU may not be able to decode the SIB due to SIBs being requestedon-demand. If a WTRU does not request the SIB that another WTRU needs,this particular SIB may not be transmitted in those time location, andthe WTRU may not find decode the SIB because the SIB is absent.

SIB overhead may be reduced using a common control channel. Because SIBdelivery using a common control channel or using a dedicatedWTRU-specific control channel each has its own advantages anddisadvantages in terms of signaling overhead and latency to receive theSIB depending on the number of WTRUs in a system, a system may use aswitching mechanism between using a common control channel and using aWTRU-specific control channel.

In an embodiment, a gNB uses both a common control channel and aWTRU-specific control channel for SIB delivery. When the number of WTRUsin communication with a gNB is above a threshold and signaling overheadis high, the gNB switches to a common control channel scheme that usespredefined time locations for SIB transmissions. Otherwise, the gNBswitches to a dedicated WTRU-specific control channel scheme that usesaperiodic time locations for SIB transmissions.

In an embodiment, system information may be transmitted before and aftera random access procedure. More particularly, non-essential systeminformation is transmitted in a random access channel and non-essentialinformation is transmitted in a random access response channel. Thisembodiment may be combined with a selective beam sweep.

When a small number of WTRUs access a cell or a carrier, random accessresponse control signaling may be used to reduce the overhead. Becausethe system information transmission overhead caused by a beam sweep maybe high, sending system information in response to a request from a WTRUvia a RACH random access response (RAR) in a RACH procedure to reducetransmission overhead. This is beneficial when the number of WTRUs issmall for a cell or a beam.

A WTRU may use a preamble or a RACH resource to request a SIBtransmission. Hereinafter, the terms preamble and RACH resource are usedinterchangeable. When a gNB receives the preamble, the gNB may use arandom access response for a SIB transmission (or system information).The preamble contains system information or SIB request information.

The WTRU may detect the random access response to obtain the SIBtransmission. A PDCCH masked with a RA-RNTI may be used to schedule aPDSCH for a SIB transmission. When multiple WTRUs use the same time andfrequency resources, the same RA-RNTI may be used for the WTRUs when aPDCCH is transmitted. Accordingly, multiple WTRUs may receive the samePDCCH with the same RA-RNTI. The WTRU that requests the SIB transmissionmay try to decode the PDCCH with the RA-RNTI. Although the SIB is alsotransmitted to other WTRUs with the same RA-RNTI, the other WTRUs mayignore the SIB by not decoding it. If the other WTRUs also need the sameSIB, the system information may be shared among these WTRUs using therandom access response.

In an embodiment, a WTRU may use only a preamble (e.g., a preambleresource, a preamble sequence, and the like) to request systeminformation. The system information that is requested is any one or acombination of system information, a set of system information, a SIB, aset of SIBs, and the like. The system information is received in a SIBtransmission.

The preamble may carry or contain SIB request information wheredifferent preambles, such as resources or sequences, may indicatedifferent SIB requests. For example, preamble # x may be used toindicate or request SIB # x. As described herein, a preamble may be apreamble sequence or a preamble resource or combination of a preamblesequence and a preamble resource. A preamble resource may be any one ora combination of a preamble time resource, a preamble frequencyresource, and a preamble spatial resource.

One or more preambles, such as one or more preamble sequences orpreamble resources may be used to indicate different SIB requests. Forexample, preamble sequence # x may correspond to SIB # x and a WTRU mayuse preamble sequence # x to request SIB # x. When a WTRU wants torequest SIB #x, the WTRU may select preamble sequence #x and transmitthe selected preamble sequence #x.

In another example, preamble time resource # x may correspond to SIB # xand a WTRU may use preamble time resource # x to request SIB # x. When aWTRU wants to request SIB # x, the WTRU may select preamble timeresource # x and transmit the preamble sequence in preamble timeresource # x.

In another example, preamble frequency resource # x may correspond toSIB # x and a WTRU may use preamble frequency resource # x to requestSIB # x. When a WTRU wants to request SIB # x, the WTRU may selectpreamble frequency resource # x and transmit the preamble sequence inpreamble frequency resource # x.

The terms preamble, preamble resource, PRACH resource, and RACH resourcemay be used interchangeably.

There may be an association between a preamble and a SIB. There may bean association between a preamble resource and a SIB. The preambleresource may be any one or a combination of a preamble time resource, apreamble frequency resource, and a preamble sequence.

An association between a preamble sequence and a SIB may be used. In anexample association, one preamble may be associated with one SIB.Preamble sequence # x may be associated with SIB # x. When a WTRU wantsto request SIB#x, the WTRU may select preamble sequence # x and transmitthe selected preamble sequence. In another example association, onepreamble may be associated with multiple SIBs. Preamble sequence # x maybe associated with SIB # x and SIB # y. When a WTRU wants to requestSIB#x or SIB#y, the WTRU may select preamble sequence # x and transmitthe selected preamble sequence. In yet another example association,multiple preamble sequences may be associated with one SIB. Preamblesequence # x and #y may be associated with SIB # x. When a WTRU wants torequest SIB#x, the WTRU may select preamble sequence # x or #y andtransmit either preamble sequence # x or #y. The WTRU may transmit bothpreamble sequence # x and #y when multiple preamble sequencetransmission is used or enabled.

An association between a preamble time resource and a SIB may be used.In an example association, one preamble time resource may be associatedwith one SIB. Preamble time resource # x may be associated with SIB # x.When a WTRU wants to request SIB#x, the WTRU may select preamble timeresource # x and transmit the preamble sequence. In another exampleassociation, one preamble time resources may be associated with multipleSIBs. Preamble time resource #x may be associated with SIB # x and SIB #y. When a WTRU wants to request SIB#x or SIB#y, the WTRU may selectpreamble time resource # x and transmit the preamble. In yet anotherexample association, multiple preamble time resources may be associatedwith one SIB. Preamble time resources # x and #y may be associated withSIB # x. When a WTRU wants to request SIB#x, the WTRU may selectpreamble time resources # x or #y and transmit the preamble. The WTRUmay transmit the selected preamble in both preamble time resources # xand #y when multiple preamble time resources transmission is used orenabled.

Similarly, an association between a preamble frequency resource and aSIB may be used. Likewise, an association between a preamble timeresource, a preamble frequency resource, and a preamble sequence and aSIB may be used.

If a WTRU is indicated with the association between a preamble (e.g., asequence, a resource, and the like) and a SIB, the WTRU may use thepreamble to request the SIB. If a WTRU is not indicated with theassociation for the preamble and the SIB, the WTRU may use a controlfield in a payload (e.g., RACH message 3) to request SIB.

A single association or mapping may be used to indicate the associationbetween a preamble and a SIB. An association indication of 1 bit may beused. A WTRU may be indicated either with or without association. Forexample, “1” may indicate “with association” and “0” may indicate“without association”.

Alternatively, more than one associations or mappings may be used toindicate the association between a preamble and a SIB. An associationindication of N bits may be used. Two options may be used. In oneoption, two indicators may be used, a first indicator (e.g., 1 bit) mayindicate “with” or “without” association and a second indicator (e.g., Nbits) may indicate which association should be used if the WTRU receivethe first indicator indicating “with” association. In the other option,a single indicator (e.g., N bits) uses joint coding of “with” and“without” association and multiple associations. For example, a 2-bitsingle indicator may be used to indicate 3 associations. In the example,“00” may indicate “without” association, “01” may indicate “association1”, “10” may indicate “association 2”, and “11” may indicate“association 3”.

Association indication may be part of RACH configuration and associationindication may be carried or included in broadcast signal or channel,such as a synchronization signal (SS), remaining minimum systeminformation (RMSI), a NR-PBCH, or other system information (OSI).

In an embodiment, a WTRU may use a preamble with an additional controlfield where the control field is used to request additional systeminformation or SIBs. The control field may or may not be attached to thepreamble. The control field may be sent separately from the preamble.The control field may be included in a payload (e.g., RACH message 3).For example, a preamble may be in one RACH message (e.g., RACH message1) and the control field may be sent in another RACH message (e.g., RACHmessage 3). The control field may contain a REQ or a SIB requestcommand. One or more bits may be used in the control field (e.g.,SIB_REQ_FIELD) to indicate a number of SIBs. For example, in order toindicate 20 SIBs, a 5 bit control field may be used. In another example,the preamble may be used to request system information or one or moreSIBs and the control field may be used to request additional systeminformation or one or more additional SIBs.

In an embodiment, a WTRU may use a preamble with an attached controlfield where the joint preamble and control field are used to requestsystem information or SIB transmissions. The preamble may be dividedinto M preamble groups where each group indicates a SIB or a category ofSIB. The category of SIB may be based on priority or importance. Forexample, preamble group 1 may be used for essential or urgent SIBs andpreamble group 2 may be used for the SIBs that are not in the categoryof essential or urgent SIBs. In another example, preamble group 1 may beused for the most critical or urgent SIBs, preamble group 2 may be usedfor moderate critical or less urgent SIBs, and preamble group 3 may beused for the least critical or low priority SIBs. After the category ofSIBs is indicated, a particular SIB may be indicated using the controlfield. One or more bits in the preamble may be used as a control field(e.g., SIB_REQ_FIELD) to indicate a number of SIBs. For example, inorder to indicate 18 SIBs with three preamble groups where each preamblegroup has three SIBs categories of 6 SIBs each, a 3 bit control fieldmay be used to indicate the 6 SIBs in each category. The SIBs may bealso be jointly indicated using a preamble and a preamble group.

In an embodiment, a WTRU may use a SR, a MAC control element (CE), aPUCCH, a PUSCH, or another UL signal to request system information or aSIB transmission.

In an embodiment, system information is multiplexed before beingsignaled. For example, essential system information and non-essentialsystem information may be multiplexed together with other signals (e.g.,a SYCH signal).

A broadcast channel (BCH) may use transmit or beam diversity because theinformation on different beams is the same. For example, cyclic delaydiversity (CDD) or STBC, SFBC or the like may be used. Furthermore, agNB or a TRP may transmit different broadcast beams using a combinationof transmit diversity at different sub-bands.

After a WTRU acquires synchronization and a NR cell ID, the WTRU maydecode a PBCH to acquire the essential system information. To supportfast access, the same PBCH may be repeated over multiple beams. Withinthe same beam, the time-frequency resource for the PBCH may be linkedwith a SS. The PBCH and the SS may be within the same SS/PBCH block. ThePBCH and the SS may be multiplexed in FDM or TDM manner. In a TDMscheme, the frequency resource for carrying the PBCH and the SS may beminimized in order to support the WTRUs with narrow bandwidth. In a FDMscheme, access delay may be reduced but a larger minimum bandwidth maybe required for a WTRU.

In an embodiment, a periodic SR is used to request a SIB transmission ifan UL control channel is not scheduled. For example, in a SR with QPSK,a first bit is indicates SR and a second bit indicates SI B_REQ.

In an embodiment, a WTRU-specific uplink control signal is used torequest a SIB transmission if an UL control channel is scheduled. Forexample, a PUCCH or the like may be used to transmit a SIB request. APUCCH format X may be used for the SIB request and the PUCCH format Xincludes a control filed for SIB request (i.e., SIB_REQ). The controlfield may be a 1 bit control field. If a PUSCH is scheduled in the sametimeslot in the uplink, the control filed for SIB request may bepiggybacked in a data channel and transmitted in the PUSCH without beingtransmitted in PUCCH.

FIG. 19 shows a flow chart diagram of an example of method for use in agNB and one or more WTRUs for signaling system information in responseto a request from a WTRU.

As described above and in diagram 1900, a gNB transmits a broadcastsignal including system information 1910. The broadcast signal may betransmitted in one or more directional beams. The broadcast signal maybe an always-on signal. The broadcast signal may be transmitted over aPBCH or a similar channel. The broadcast signal may also be transmittedover a channel carrying remaining minimum system information (e.g.,NR-PDSCH). The system information included in the broadcast signal mayprovide configuration information, which includes any one or acombination of a resource allocation, mapping information, a resourceindication, and a mode indication directing the behavior of the WTRU.The configuration information may include an indication regardingwhether the WTRU is able to transmit any one or a combination of arequest signal, a feedback signal, or neither to the gNB. Theconfiguration information may allow the WTRU to request systeminformation or one or more SIB transmissions. The configurationinformation may be part of RACH configuration or different from RACHconfiguration. The configuration information may be carried or includedin broadcast signal or channel, such as a synchronization signal (SS),remaining minimum system information (RMSI), a NR-PBCH, or other systeminformation (OSI). The system information may be referred to as firstsystem information or remaining minimum system information.

A WTRU receives the system information in the broadcast signal 1920. TheWTRU then determines configuration information using the broadcastsignal in order to request system information 1930. In an example, theWTRU determines whether the WTRU may transmit any one or a combinationof a request signal, a feedback signal, or neither to the gNB in asignal.

The WTRU transmits a signal using the configuration informationassociated with the received system information 1940. In an embodiment,the transmitted signal is a request signal. The transmitted signal mayinclude a preamble. The preamble may be referred to as a preamblesequence or a preamble time/frequency resource. The preamble in thetransmitted signal may contain or indicate system information requestinformation. The preamble may be associated with one or more SIBs. In anembodiment, the preamble is associated one or more groups of SIBs andeach group of SIBs may be associated with a priority level. In anembodiment, the transmitted signal includes a control field thatindicates additional SIB request information. The transmitted signal mayinclude any one or a combination of the preamble and the control field.

The gNB receives the signal from the WTRU 1950 and the gNB thentransmits system information to the WTRU 1960. The system informationreceived in response to the transmitted signal may be receivedperiodically in predefined time locations. Alternatively, the systemreceived in response to the transmitted signal may be receivedaperiodically based on the transmitted signal. The transmitted systeminformation may be referred to as second system information or othersystem information transmissions (SIBs).

Although the features and elements are described above in particularcombinations, each feature or element can be used alone without theother features and elements or in various combinations with or withoutother features and elements. For example, in an embodiment, a WTRU maybe configured to transmit including any one or a combination of afeedback signal, a request signal, and a preamble to a gNB to request asystem information transmission or SIB.

Although the solutions described herein consider LTE, LTE-A, NR or 5Gspecific protocols, it is understood that the solutions described hereinare not restricted to this scenario and are applicable to other wirelesssystems as well.

1. A method for use in a wireless transmit/receive unit (WTRU) forreceiving system information, the method comprising: receiving abroadcast signal from a gNB, wherein the broadcast signal includes firstsystem information; determining configuration information associatedwith the received first system information; transmitting a signal to thegNB using the determined configuration information; and receiving secondsystem information from the gNB in response to the transmitted signal.2. The method of claim 1, wherein the second system information is oneor more system information blocks (SIBs).
 3. The method of claim 1,wherein the configuration information includes an indication regardingwhether the WTRU is able to include any one or a combination of arequest signal or a feedback signal in the signal transmitted to thegNB.
 4. The method of claim 1, wherein the transmitted signal to the gNBincludes a preamble that indicates SIB request information.
 5. Themethod of claim 4, wherein the configuration information includesmapping information that provides an association between the preambleand the second system information.
 6. The method of claim 1, wherein thetransmitted signal to the gNB includes a control field that indicatesadditional SIB request information.
 7. The method of claim 1, furthercomprising determining whether the received first system informationsatisfies reception criteria, wherein the first system information isreceived from the gNB in one or more directional beams.
 8. The method ofclaim 7, wherein the transmitted signal to the gNB includes a feedbacksignal that provides feedback for the one or more directional beams, thefeedback including any one or a combination of beam informationassociated with the WTRU and an indication regarding whether thereceived first system information satisfies reception criteria.
 9. Themethod of claim 8, wherein the reception criteria includes a detectedenergy of the first system information being above a predeterminedthreshold.
 10. The method of claim 8, wherein the reception criteriaincludes a cyclic redundancy check (CRC) associated with the firstsystem information being passed.
 11. A wireless transmit/receive unit(WTRU) comprising: an antenna and a transceiver configured to receive abroadcast signal from a gNB, wherein the broadcast signal includes firstsystem information; and a processor configured to determineconfiguration information associated with the received first systeminformation; wherein the antenna and the transceiver are furtherconfigured to transmit a signal to the gNB using the determinedconfiguration information and to receive second system information fromthe gNB in response to the transmitted signal.
 12. The WTRU of claim 11,wherein the second system information is one or more system informationblocks (SIBs).
 13. The WTRU of claim 11, wherein the configurationinformation includes an indication regarding whether the WTRU is able toinclude any one or a combination of a request signal or a feedbacksignal in the signal transmitted to the gNB.
 14. The WTRU of claim 11,wherein the transmitted signal to the gNB includes a preamble thatindicates SIB request information.
 15. The WTRU of claim 14, wherein theconfiguration information includes mapping information that provides anassociation between the preamble and the second system information. 16.The WTRU of claim 11, wherein the transmitted signal to the gNB includesa control field that indicates additional SIB request information. 17.The WTRU of claim 11, further the processor is further configured todetermine whether the received first system information satisfiesreception criteria, wherein the first system information is receivedfrom the gNB in one or more directional beams.
 18. The WTRU of claim 17,wherein the transmitted signal to the gNB includes a feedback signalthat provides feedback for the one or more directional beams, thefeedback including any one or a combination of beam informationassociated with the WTRU and an indication regarding whether thereceived first system information satisfies reception criteria.
 19. TheWTRU of claim 18, wherein the reception criteria includes a detectedenergy of the first system information being above a predeterminedthreshold.
 20. The WTRU of claim 18, wherein the reception criteriaincludes a cyclic redundancy check (CRC) associated with the firstsystem information being passed.